There have been waves of truth and heresy throughout church history. but consider that the bulk of Christianity throughout history has agreed on the core issues and teachings primarily because they are relying solely on the Bible. It's revelation must be quite complete for so many individuals and groups throughout so many centuries to have concluded the same essential doctrines. Surely we can rely on the Bible's presentation of who Christ is, what He did and why He came, as well as all other spiritual truths.
Any later revelations or books must be judged by the Bible and must agree with it because God does not change. But obviously there are differences in what the "cults" teach or else there would be no definition for "Cult of Christianity" like the one above.
Did the work of Christ truly only produce the small number of followers in your group? Or did He indeed change the face of the planet and effect billions?! I know that "narrow is the way and few are they that find it", but are you so sure that your group is the only one that found it?
The Bible says that the test of spiritual truth would center around who people profess Christ to be. Your eternity depends on your discernment of this critical truth.
As a fast way for you to get started investigating the central teachings that the above definition is referring to, rather than looking at them academically, why not consider them personally?